Compounds such as 2-hydroxyphenyl lower alkyl ketones, e.g. 2-hydroxyacetophenone (2-HAP) are possible intermediates for a variety of products having different end uses. Thus 2-HAP may be converted into catechol (1,2-dihydroxybenzene) by first reacting the 2-HAP to form the monoacetate ester of catechol using a "Baeyer-Villiger" oxidation as disclosed, for example in application Ser. No. 661,552, filed Oct. 17, 1984 and the references cited therein, and then converting the monoacetate ester to catechol by hydrolysis, e.g. as disclosed in the previously cited application Ser. No. 661,552, or by transesterification as disclosed in Ser. No. 689,533, filed Jan. 7, 1985 and the references cited therein. Alternatively, the 2-HAP can be converted into guaiacol by first methylating it to form 2-methoxyacetophenone, and then obtaining the acetate ester of the monomethyl ether of catechol by a Baeyer-Villiger oxidation and the guaiacol by hydrolysis or transesterification as previously described for catechol. Aspirin may be made from 2-HAP by first acetylating it with acetic anhydride to yield 2-acetoxyacetophenone and oxidizing the latter compound with a transition metal catalyst to form aspirin; these reactions are disclosed in application Ser. No. 633,832 filed July 24, 1984 and the references cited therein.
The reaction of phenol and acetic acid under certain specifically defined conditions to obtain hydroxyacetophenones is disclosed in application Ser. No. 06/716,016 filed Mar. 26, 1985. Cited in this application are the following published references with teachings of the reaction of phenol and acetic acid to form 4-hydroxyacetophenone (4-HAP), as described:
Dann and Mylius in a dissertation included as part of a series of Reports from the Institute for Applied Chemistry of the University of Erlangen, received for publication on Jan. 7, 1954 and published in Annalen der Chemie 587 Band, pages 1 to 15, disclose the reaction of phenol and glacial acetic acid in the presence of hydrogen fluoride to produce 4-hydroxyacetophenone (4-HAP) in a yield of 61.6%. This reaction may be conventionally characterized as a Friedel-Crafts acetylation of phenol with acetic acid as the acetylating agent.
Simons et al, Journal of the American Chemical Society, 61, 1795 and 1796 (1939) teach the acylation of aromatic compounds using hydrogen fluoride as a condensing agent and in Table 1 on page 1796 show the acetylation of phenol with acetic acid to produce p-hydroxyacetophenone (4-HAP) in 40% yield.
None of the foregoing disclosures, however, teach any method of reacting phenol with acetic acid in the presence of a silicalite catalyst to obtain a product comprising of 2-HAP.
The prior art also discloses the Fries rearrangement of phenyl acetate to form hydroxyacetophenones. For example, the previous cited Dann and Mylius article shows the rearrangement of phenyl acetate in hydrogen fluoride to 4-hydroxyacetophenone, with a maximum yield of 81% after 24 hours of reaction time, and report a yield of 92% stated to be obtained by K. Weichert as reported in Angewandte Chemie 56, 338 (1943). Although Dann and Mylius suggest that the difference in yields may be at least partly due to the previous ignoring by Weichert of the accompanying 2-hydroxyacetophenone, the latter is nevertheless produced in only minor amounts as compared with the 4-hydroxyacetophenone.
Davenport et al, U.S. Pat. No. 4,524,217, disclose a process for the production of N-acetyl-para-aminophenol (acetaminophen) including the Fries rearrangement of phenyl acetate with a hydrogen fluoride catalyst to produce a preponderance of 4-hydroxyacetophenone.
Thus, none of these references discloses a method for carrying out a Fries rearrangement of phenylacetate in the presence of a silicalite catalyst to produce 2-hydroxyacetophenone.